Lesson 8 of 40 Performance Advanced 45 min

Performance Profiling & Diagnostics

Use the VS 2026 Diagnostics Hub, CPU profiler, memory profiler, and the new AI performance advisor to eliminate bottlenecks.

Part 1: The Diagnostics Hub

Open via Debug → Performance Profiler (Alt+F2). Available tools:

CPU Usage — flame graphs and call trees
Memory Usage — heap snapshots and leak detection
Async Timing — visualize async/await overhead
Database Queries — EF Core query analyzer
Network — HTTP request timeline

Part 2: CPU Flame Graphs

Flame graphs show where CPU time is spent. Wider = more time. In VS 2026's profiler:

Use Record CPU Profile during a realistic workload
Filter by thread or time range
Click any function to navigate to source
Copilot can explain hotspots in plain English

Part 3: Memory Leak Detection

// Take two heap snapshots:
// 1. Baseline (after warm-up)
// 2. After suspected leak operation

// Compare snapshots — objects only in snapshot 2
// are candidates for leaks

// VS 2026: AI flags EventHandler leaks automatically
// "⚠ 23 instances of EventHandler not unsubscribed"

Part 4: BenchmarkDotNet Integration

VS 2026 integrates BenchmarkDotNet directly into the IDE:

[MemoryDiagnoser]
public class StringBenchmarks
{
  [Benchmark]
  public string Concat() => "a" + "b" + "c";

  [Benchmark]
  public string Interpolate() => $"{"a"}{"b"}{"c"}";
}

Run benchmarks via right-click → Run Benchmarks.